Slip clutch



July 27, 1965 A, QRR, SR 3,195,637

SLIP CLUTCH Filed July 9, 1963 United States Patent 3,196,637 SLIP CLUTCH John A. Grr, Sr., Chicago, Ill., assignor to J. A. Orr Company, Inc., a corporation of Illinois Filed July 9, 1963, Ser. No. 293,624 7 Claims. (Cl. 64-30) This invenion relates to drive mechanisms, and, in particular, to slip clutch means for use in rotating drive mechanisms. V

In the rotary type power lawn mowers, an elongated cutter blade is centrally mounted on the lower end of a drive shaft driven by a 'suitable drive means, such as a gasoline engine or the like. by the drive means at a high rate, and is provided along its leading portions with a sharp grass cutting edge. In the normal cutting of the grass by theblade, no problem is encountered, but at times objects may be encountered by the blade tending to stop rotation of the blade, thereby introducing substantial twisting forces to the blade connected to the shaft and to the shaft itself. In many instances such forces have been found to deform the shaft, requiring expensive replacement thereof. In other instances, the connection of the blade to the shaft has been broken.

The present invention comprehends an improved coupling structure for yieldably mounting the elongated cutter blade to the lower end of the drive shaft precluding damage to the apparatus, notwithstanding the encountering of rotation-stopping objects. Thus, `a principal object of the present invention is the provision of a new and improved structure for yieldably mounting an elongated blade on a rotatable shaft.

A Vfurther object is to provide such` a structure which is simple and economical of construction, yet which has long useful life under the adverse conditions encountered in such apparatus.` A

A Vfurther object of the invention is the provision of such a structure including a bronze, adapter means iixedly retainingl the blade in driven association withthe shaft and arranged to permit ready disconnection therebetween in the event that the blade rotation is stopped or substantially slowed while the shaft rotation is maintained.

A still further object of the invention is the provision of such structure including an elongate channel having a web, spaced'side anges, and a pair of opposed, spaced spring fingers extending from the web to adjacent the perpendicular centerline of the web, the channel being arranged to receive the blade therein with the blade ends projecting substantially from the opposite ends of the channel and the central opening lof the blade aligned with the perpendicular centerline of the web, an adapter arranged to be fixed to the end of the shaft, the adapter having an axial opening, a bolt extending through the space between the fingers, the blade opening, and theadapter opening and having a first end portion arranged to be coaxially secured to the rotatable shaft end and an opposite end portion, force applying means associated with the opposite end portion engaging the opposed spring fingers to urge the channel toward the first end of `the bolt and thereby urge the blade carried in the channel into frictional engagement with the adapter, and anannular spacer concentrieally around the bolt and extending axially outwardly from the adapter to limit the movement of the `force applying means toward the adapter to limit the force of frictional engagement between the blade and the adapter to a preselected value.

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a fragmentary perspective view of a lawn The cutter blade is rotated mower provided with a blade connecting structure embodying the invention;

FIGURE 2 is a fragmentary enlarged bottom plan view thereof;

FIGURE 3 is a fragmentary vertical section taken substantially along the line 3 3 of FIGURE 2; and

FIGURE 4 is a fragmentary transverse vertical section taken substantially along the line 4--4 of FIGURE 3.

In the exemplary embodiment of the invention, as disclosed in the drawing, a lawn mower generally designated 10 is shown to include a depending drive shaft 11 driven by a suitable drive device, herein illustratively a conventional gasoline engine 12. The mower includes a conventional protective housing 13 provided with a plurality of suitable wheels 14 for guiding the mower over the area to be mowed, such as a lawn or the like. The housing 13 may be provided with aconventional discharge chute 15 arranged` to pass grass and the like cut by a blade 16 carried on the lower end 17 of the shaft 11.

The present invention is concerned with the means for connecting the blade 16 to the shaft end 17, and is more specifically shown in` FIGURES 2 through 4. Therein, the connecting means generally designated 18 is shown to comprise a blade adapter 19 retained against rotation onV the lower shaft end 17-by suitable means, such as key 20.Y

The adapter 19 is provided at its lower endwith an inturnedV annular flange 21 overlying the shaft end 17 and defining a central opening 22 coaxially aligned with the shaft end. The lower end of the adapter further defines an outturned flange 23 anda downwardlyfacing annular friction surface 24. The total area of the surface 24 is determined by the internal diameter of the ange 21, and the externaldiameter of the il'ange 23 which is preferably substantially equal to the width of the blade 16. The adapter is preferably formed of a .tear resisting material and herein is formed of bronze.

The blade 16 is providedwith a conventional 4central hole 25. The blade is retained in facial engagement with the surface 24, with the hole 25 coaxially aligned with shaft 1 1,.by means of a channel 26 and cooperating bolt. 27. More specifically, channel.V 26 comprises' an elongated member having a web portion 28`and spaced upwardlyprojecting side anges 29. The spacing betweenfianges 29, as best 'seen in FIGURE 2, is substantially equal to the width of blade 16, and the height of the side flanges is slightly greater than the thickness of the blade; The channel preferably has a substantial length so as to extend substantially laterally relative to the adapter 19, thereby providing a firm support for the blade 16.

As best seen in FIGURES 2 and 3, the web 28 of the channel 26 is provided centrally with a pair of downwardly struck opposed spring fingers 30 extending to adjacent the perpendicular centerline 31 of the web 2S. The bolt 27 includes a threaded shank portion 32 coaxially threaded to the lower end 17 of shaft 11, and extending downwardly therefrom through the opening 22 of adapter 19, the hole 25 of the blade 16, and between the fingers 30, with the enlarged head 33 of the bolt being disposed below the lingers 30.

. A bronze washer 34is carried on the bolt between the head 33 and the lingers 30 to be urged `by the bolt head upwardly against the lingers when the bolt is suitably threaded into the shaft end 17` to bias the channel 26 upwardly and thereby urge the blade 16 into frictional facial engagement-with the adapter surface 24. A suitable lock washer 35 may be interposed between the bronze washer 34 and-the bolthead 33 to preclude loosening of the bolt. i N i A tubular spacer 36 may be provided in concentrically surrounding relationship to the bolt, extendingbetween the lower surface 24 of the blade adapter 19` and the Patented July 27, 1965 aaneen? bronze washer 34 to limit the upward movement of the spring fingers 36 as an incident of the threading of the bolt into the shaft end, thereby limiting the force of frictional engagement of the blade 16 with the adapter surface 24. As shown in FIGURE 3, the spacing between the fingers 30 is greater than the outside diameter of the vspacer 36, and the length of the spacer 36 is less than (herein 1/16 inch less than) the spacing between the adapter surface 24 and the bottom surface 30a of the spring fingers 30 prior to the tightening of bolt 27; Thus, the` fingers 30 may be urged resiliently upwardly by the adjustment of the bolt 27 until washer 34 abuts the lower end of the spacer.

Thus, slip connector 1-8 comprises a simple and economical device for mounting the blade 16. To install the blade by means of connector 18, the blade is firstly laid in channel 26with the opening 22 centrally located. The adapter 19 is installed on the lower end of the drive shaft and the assembled blade and channel are secured to the drive shaft by means of the bolt 27, previously having the spacer 36installed therearound. The bolt is threaded into the shaft end 17 until washer 34 abuts spacer 36 whereby the desired frictional surface engagement of the blade 16 Vwith the adapter surface 24 and washer 343 is provided. As shown in FIGURE 3, the bolt head may beV Aprovided with a suitable screw driver slot 37 for facilitated adjustment thereof in applying the frictional orce.

As indicated above, the invention comprehends the provision of an adapter having optimum rabrasion and tear resistance, whereby repeated slipping operations may occur in Vthe use .of the device without substantial impairment of the desired frictional retentionof the blade in 'association with the adapter.

The connector 18 permits facilitated disassembly such as for sharpening of the blade or similar maintenance of the apparatus when desired. f

While l have shown and described one embodiment of my invention, it is to be understood that it is capable of Ina-ny modifications. Changes, therefore, in the construction and arrangement maybe made without departing from the Vspirit and scope of the invention as defined in the appended claims.

I claim: Y

'1. Structure for yieldably mounting an elongated blade having a central opening on one end of a rotatable shaft, comprising: an elongate channel having a web, spaced side flanges, and a pair of opposed, spaced spring fingers extending from said web to .adjacent the perpendicular centerline of the web, said channel being arranged to receive the blade therein with the blade ends projecting substantially from the kopposite ends of the channel and the `central opening of the blade aligned with said perpendicular centerline of the web; an adapter .arranged to be fixed tothe end of the shaft, said adapter having an axial opening; a bolt extending through the space between said fingers, the blade opening, and the adapter opening and having a first end portion arranged to be coaxially secured to the rotatable shaft end and an lopposite end portion; force applying -means associated with said opposite end portion engaging said opposed spring fingers to urge the channel toward said first end of the bolt and thereby urge Y the blade carried in said channel into frictional engagement with saidadapter; .and an annular spacer concentr-ically around the bolt and extending axially outwardly from the adapter to limit the movement of said force applying means toward said adapter to limit the force lof frictional engagement between the` blade and the adapter to a preselected value.

2. The blade mounting structure of claim 1 wherein vsaid adapter is formed of an alloy resisting tearing deformation by said blade, such as bronze. l

3. The blade mounting structure of claim 1 wherein said channel extends longitudinally substantially outwardly from said adapter.

4. The blade mounting structure Iof claim 1 wherein said force applying means includes a ring formed of an alloy such as bronze urged by the bolt against said spring fingers.

5. Structure for yieldably mounting an elongated blade having a central opening on one end of a rotatable shaft, comprising: an elongate channel having a web, spaced side anges, and a pair of opposed, spaced lspring fingers formed integrally with and extending from said web to adjacent the perpendicular centerline korf-the web, said `channel being arranged to receive the blade therein with the blade ends projecting substantially from the `opposite ends -of the channel and the central opening of the blade aligned with said perpendicular centerline yof the web; a bronze adapter arranged to be fixed to the end of the shaft, said adapter having Yan axial opening; a bolt extending through the space between said fingers, the blade opening, and the adapter opening and having a first end portion arranged to be coaxially secured to the rotatable vshaft end and an opposite, enlarged end portion; a bronze ring engaged by said enlarged end portion and engaging said opposed spring fingers to urge the channeltoward said Iadapter and thereby urge the blade carried in said channel into frictional engagement with said adapter; a lock washer between said enlarged end por-tion of the bolt and said bronze ring; and an annular spacer concentrically around the bolt and extending axially outwardlyV from the adapterv to engage the shaft end and limit the movement of said force applying means toward said adapter thereby to limit the force of frictional engagement between the blade and theY adapter to a preselected Value. Y u

' 6. The blade mounting structure of claim 5 wherein said adapter has a circular surface portion Vconfronting the blade having a diameter substantially equal to the width ofthe blade. f

7. Structure for yieldably mounting an elongated blade having a central opening on one end of a rotatable shaft, comprising: an elongate channel having a web, spaced side flanges, and a pair of opposed, spaced spring fingers integrally formed from and extending fr-om said web to adjacentthe perpendicular centerline of the web, said channel being arranged to receive the blade therein wit-h the blade ends projecting substantially from the opposite ends of the channel and the central opening of the blade aligned with said perpendicular centerline of the web; an adapter arranged to be fixed to'the end of the shaft, said .adapter having an axial opening; a bolt extending through the space between lsaid fingers, the blade opening, and the adapter opening and having a rst end portion arranged to be coaxially secured to the rotatable shaft end and an opposite end portion; force applying means associated with said opposite end portion engaging said opposed spring fingers to urge the channel toward said first end of the bolt and thereby urge the blade carried in said channel into frictional engagement with said adapter; andan annular spacer concentrically around the bolt and extending axially outwardly from the adapter to limit the movement of said force applying means toward said adapter to limit the force of frictional engagement between the blade and the adapter to a preselected value.

References Cited bythe Examiner UNITED STATES PATENTS 2,685,160 8/54 Kuhary et al. 64-30 2,862,376 v12/58 Thelander 64-30 2,862,737 3/61 Pearson 56-25.4 2,976,666 3/61 MacI-Ilovec 56-25.4

ROBERT C. RroRDoN, Primary Examiner. 

1. STRUCTURE FOR YIELDABLY MOUNTING AN ELONGATED BLADE HAVING A CENTRAL OPENING ON ONE END OF A ROTATABLE SHAFT, COMPRISING: AN ELONGATE CHANNEL HAVING A WEB, SPACED SIDE FLANGES, AND A PAIR OF OPPOSED, SPACED SPRING FINGERS EXTENDING FROM SAID WEB TO ADJACENT THE PERPENDICULAR CENTERLINE OF THE WEB, SAID CHANNEL BEING ARRANGED TO RECEIVE THE BLADE THEREWIN TWITH THE BLADE ENDS PROJECTING SUBSTANTIALLY FROM THE OPPOSITE ENDS OF THE CHANNEL AND THE CENTRAL OPENING OF THE BLADE ALIGNED WITH SAID PERPENDICULAR CENTERLINE OF THE WEB; AN ADAPTER ARRANGED TO BE FIXED TO THE END OF THE SHAFT, SAID ADAPTER HAVING AN AXIAL OPENING; A BOLT EXTENDING THROUGH THE SPACE BETWEERN SAID FINGERS, THE BLADE OPENING, AND THE ADAPTER OPENING AND HAVING A FIRST END PORTION ARRANGED TO BE COAXIALLY SECURED TO THE ROTATABLE SHAFT END AND AN OPPOSITE END PORTION; FORCE APPLYING MEANS ASSOCIATED WITH SAID OPPOSITE END PORTION ENGAGING SAID OPPOSED SPRING FINGERS TO URGE THE CHANNEL TOWARD SAID FIRST END OF THE BOLT AND THEREBY URGE THE BLADE CARRIED IN SAID CHANNEL INTO FRICTIONAL ENGAGEMENT WITH SAID ADAPTER; AND AN ANNULAR SPACER CONCENTRICALLY AROUND THE BOLT AND EXTENDING AXIALLY OUTWARDLY FROM THE ADAPTER TO LIMIT THE MOVEMENT OF SAID FORCE APPLYING MEANS TOWARD SAID ADAPTER TO LIMIT THE FORCE OF FRICTIONAL ENGAGEMENT BETWEEN THE BLADE AND THE ADAPTER TO A PRESELECTED VALUE. 